1. Field of the Invention
The present invention relates generally to air dryers, and more specifically to a manifold system for connecting two or more air dryers into a single assembly.
2. Description of Related Art
Pneumatic braking systems are widely used in heavy-duty vehicles such as buses, trucks, and trailers. Such a system typically includes, at a minimum, an air compressor for producing pressurized air, a reservoir for storing pressurized air, and an air dryer for removing moisture and other contaminants from the air flowing through the system.
The air dryer is an essential element of the system as it removes moisture and contaminants that would otherwise degrade the operation of the various components of the braking system. One common type of conventional air dryer includes a dryer body having a removable desiccant cartridge and supply, delivery, and control ports. In normal operation, pressurized system air is directed to the supply port on the dryer body where passageways and an inner chamber formed in the body route the supply air to the desiccant cartridge. The desiccant cartridge traps moisture and other contaminants in solid, liquid and vapor form. From the desiccant cartridge, the clean, dry air flows through the dryer body to the delivery port and on to the remainder of the pressurized air system.
Typical air dryers also operate in a regeneration or purge mode where air is routed in a reverse direction through the desiccant cartridge to expel trapped contaminants and moisture from the cartridge. Applying pressurized air to the control port of the dryer body actuates a purge valve in the dryer body so that air from the system reservoir is directed in a reverse direction through the desiccant cartridge. The reverse flowing air is typically vented through a purge port to the atmosphere along with the previously trapped moisture and contaminants from the desiccant cartridge.
While single air dryers are useful and serve their intended purpose, changes in the industry and changes in maintenance expectations have driven the need for additional air drying capacity. Larger vehicles, for example, typically require correspondingly larger air systems and air dryers. A desire for longer maintenance intervals of the air dryer (i.e., changing the desiccant cartridge less often) likewise requires a dryer having increased capacity.
Various ways of providing increased air drying capacity have been proposed. For example, one approach has been to simply plumb two or more single air dryers into a pressurized air system using a combination of multiple hoses and fittings. This approach has numerous drawbacks, including the relatively large amount of space required to accommodate the arrangement of external hoses and fittings and the overall complexity of the arrangement. Other drawbacks include increased reliability problems introduced by the numerous additional hoses, fittings, and joints, as well as the increased cost associated with the external plumbing and fittings.
Another approach to increasing drying capacity has been to physically increase the size of the air dryer body and/or desiccant cartridge. This approach requires not only the design and manufacture of new parts (e.g., a larger size body and larger size desiccant cartridge), but also increased inventory costs as the new parts must be maintained in inventory along with the existing parts. Furthermore, an increase in size of a desiccant cartridge does not necessarily proportionally increase the drying capacity of the cartridge. Thus a desiccant cartridge that is twice the size does not necessarily double the drying capacity or double the corresponding maintenance interval.
Yet another approach is to provide a unibody air dryer hosting two desiccant cartridges. This approach likewise requires a separate air dryer body part which must be manufactured and maintained in inventory, incurring the detrimental effects as discussed above.
Thus, it can be seen that there remains a need in the art for an air dryer having increased drying capacity.